When coal is cooked in very high temperature ovens in the absence of oxygen, the heat transforms the coal into coke which is then used as a fuel in blast furnaces to produce steel. After the coal has been turned into coke by the "coking process," it must be cooled before being sized for use in the blast furnaces. In conventional coking operations, the hot coke cake is expelled by a ram into hopper cars open to the atmosphere where it ignites and continues burning until the hot coke is quenched, typically by running the cars through a water bath to lower its temperature below the kindling temperature.
Several problems result from conventional coking operations. First, expelling the hot coke into the hopper cars pulverizes and breaks the semi-rigid coke cake into chunks smaller than the minimum acceptable size for use in the blast furnace operation. Secondly, the burning coke causes a loss of valuable coke and causes air pollution from the combustion fumes.
Quenching the burning coke with large quantities of water creates additional problems. For example, a major disadvantage with water quenching is that the wet coke has a substantially lower heating value than dry coke. Further, there is significant air pollution from the dust particles and chemicals that are carried into the atmosphere with steam that is formed when the water strikes the hot coke. Not only is the water polluted by the coke, but the coke itself is polluted by chemicals in the waste water that is typically reused in the quenching process. Finally, the quenching operation itself causes the coke to break up, further pulverizing and degrading the quality of the coke.
There have been numerous attempts by others to overcome some or all of the general problems associated with conventional wet quenching, some dating back to the nineteenth century. Approaches have included receiving the coke in substantially cake form, following by either direct or indirect water quenching. An example of the former is U.S. Pat. No. 3,748,235 to Pries, while examples of the latter are German Patent 279,950 and U.S. Pat. No. 4,285,772 to Kress. There have been several proposals involving the use of inert cooling gas to quench hot coke in closed containers. Examples of such arrangements are shown in British Patent 183,113 (1923), in German Patent 436,995 and in the Kress patent referenced above.
The Kress patent discloses a system employing a trackless, steerable vehicle which is adaptable for either grass roots coking operations or existing coke oven batteries. The present invention presents improvements on the basic system and vehicle disclosed in U.S. Pat. No. 4,285,772.